The NFL and NFL Referees Association remain at a stalemate in a labor dispute that has put replacement officials on the field for three weeks of regular-season games, sources on both sides of the discussion said Monday.

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The meetings that took place Tuesday night, Wednesday morning, Saturday and all day Sunday in New York were "high-level" discussions, according to an involved source. NFL Commissioner Roger Goodell attended the meetings Saturday and Sunday.

The most prominent issue remains the pension. The league has wanted the officials to move from a defined benefit retirement plan (pension) to a defined contribution plan (401k). The NFLRA offered the compromise of having new officials on a 401k plan, with the old officials grandfathered in under the old rules, but the league hasn't accepted that, and the parties remain apart on that issue.

There's also an economic divide, which includes the referees' desired salary, although there's some argument over how significant it is, and disagreement over the employment of full-time officials and backup crews. Multiple sources believe these issues are workable, if an agreement could be reached on the retirement plan.

Now the NFLRA wants more league owner involvement in these negotiations, according to a referee source. The NFL hasn't been asked yet to involve owners in talks, multiple sources with direct knowledge of the league's position said.